JPH0755920A - Drip-proof type ultrasonic microphone - Google Patents

Abstract

PURPOSE:To shorten a reverberation time by suppressing excitation of a printed board used also as a terminal board and to reduce a cost by commonly using a resonator and a terminal base. CONSTITUTION:A piezoelectric element 12 is fixed to an inner surface of a bottom of a bottomed cylindrical vibration case 11 to form a vibrator 1. A printed board P in which a resonator 2 is used also as a terminal base 3 is fixed to an intermediate part of a vibration case 11. Positive and negative terminals 31, 32 protruding from an opening of the case 11 protrude from an end of the board P. An elastic member 8 is filled at the opening 11a side of the case 11 of the board P in the case 11. Vibration energy of the board P having a function of the base 3 is absorbed by the member 8 thereby to attenuate reverberation due to the vibration of the board P.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission / reception integrated drip-proof ultrasonic microphone mounted on a vehicle or the like.

[0002]

2. Description of the Related Art A conventional transmission / reception integrated type drip-proof ultrasonic microphone is driven by inputting a tone burst wave into a piezoelectric ceramic at a constant or arbitrary period, as shown in FIG. In addition, the vibrating body 1, the resonator 2, the terminal base 3, and the vibration isolator 4 are the main constituent members. Such a conventional example is known from, for example, Japanese Utility Model Laid-Open No. 59-154985.

The vibrating body 1 has a piezoelectric element 12 fixed to the inner surface of the bottom of a vibrating case 11 having a cylindrical shape with a bottom. The vibrating case 11 is made of an aluminum material and serves as one conductor when the piezoelectric element 12 is driven. The piezoelectric element 12 is formed of a PZT-based piezoelectric ceramic in a disk shape, has electrodes on both sides, one surface is bonded to the vibration case 11 with an adhesive, and the other surface is connected to a lead wire. The resonator 2 is made of a metal material, has a predetermined axial length, and is formed in a ring shape. The resonator 2 is fixed near the middle of the vibration case 11 in the axial direction, and the vibration case The change in the resonance frequency when the straight pipe portion 11 is held is prevented.

The terminal base 3 has positive and negative terminals 31 and 32 which are electrically connected to the electrodes of the vibration case 11 and the piezoelectric element 12 via lead wires.
The opening 11a is engaged with the vibration isolator 4 and is fixed by the filler 5. The vibration isolator 4 is located between the resonator 2 and the terminal base 3 and is fitted to the inner circumference of the vibration case 11 to hold the terminal base 3 in engagement and prevent transmission of vibration to the terminal base 3. I'm out.

[0005]

The conventional drip-proof ultrasonic microphone having the above-described structure is installed in the back or corner of a vehicle and detects the distance between the vehicle and the obstacle while the driver is in the driver's seat. However, the following problems occur. That is, since the distance between the vehicle and the obstacle is short, the sound wave reflected by the obstacle is received at the timing when the reverberation of the vibrating body 11 is high, and as a result, the reverberation waveform and the reflection waveform are separated. The identification becomes impossible and the short-range detection performance becomes poor.

Moreover, since the resonator 2 and the vibration case 11 are rigidly fixed to each other, the resonator 2 itself is excited and the reverberation time becomes long, which causes a problem that the short distance detection performance cannot be improved. is there. Further, in the related art, the resonator 2 and the terminal base 3 which is a separate component from the resonator 2 are required,
The cost is high and the assembly is complicated.

The present invention was invented in view of the problems of the conventional example as described above, and the purpose thereof is to:
It is an object of the present invention to provide an inexpensive drip-proof ultrasonic microphone by shortening the reverberation time by suppressing the excitation of a printed circuit board that also serves as a terminal base and by sharing the resonator and the terminal base.

[0008]

A drip-proof ultrasonic microphone according to the present invention comprises a vibrating case 11 formed in a cylindrical shape with a bottom and having a taper portion on the bottom side, and a piezoelectric element 12 on the inner surface of the bottom portion of the vibrating case 11. The vibrating body 1 and the vibrating case 11 that are fixedly attached.
A printed circuit board P that also serves as the resonator 2 and the terminal base 3 that are fixed in the middle, and positive and negative terminals that project from the printed circuit board P and whose ends project from the opening of the vibration case 11. 31 and 32, and the elastic body 8 filled inside the vibration case 11 on the side of the opening 11a of the vibration case 11 of the printed circuit board P. By adopting such a configuration, The object of the present invention is achieved by solving the problems of the conventional example described above.

[0009]

According to the present invention having the above-described structure, the printed circuit board P fixed in the middle of the vibration case 11 serves as both the resonator 2 and the terminal base 3. Positive and negative terminals 31 and 32 projecting from the opening of the vibration case 11 are provided in a protruding manner, and the elastic body 8 is provided on the vibration case 11 opening side of the printed circuit board P in the vibration case 11.
Is filled, the vibration energy of the printed circuit board P having the function of the terminal base 3 due to the vibration of the vibrating body 1 at the time of wave transmission is consumed by the resistance of the vibration suppressing function of the elastic body 8 to prevent the excitation. The reverberation due to the vibration of the resonator 2 is attenuated by the timing of the wave to facilitate detection of the received signal.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the accompanying drawings. FIG. 1 shows a sectional view of a drip-proof ultrasonic microphone according to the present invention. Bottomed cylindrical vibration case 1
The piezoelectric element 12 is fixed to the inner surface of the bottom portion of the vibrating body 1. The vibrating case 11 has a shape in which a circular truncated cone portion is continuous with an end portion of a cylindrical portion, and is entirely formed of an aluminum material. The printed circuit board P is press-fitted in the middle of the vibration case 11 so as to have a function of a resonator. Further, the plus and minus terminals 31 and 32 are press-fitted and soldered to the printed circuit board P with solder 9 to give the printed circuit board P the function of the terminal base 3. As a result, the printed circuit board P serves as both the resonator 2 and the terminal base 3.

The conductive adhesive 6 applied to the outer peripheral portion of the printed circuit board P is one of the terminals 31 and 32 (in the embodiment, the negative terminal 32) and the vibrating case 11.
Is conducted via the pattern of the printed circuit board P. In addition, the lead 7 passes through an opening provided in the printed circuit board P, is soldered with the solder 9, and the other terminal of the terminals 31 and 32 (in the embodiment, the plus side is provided) via the pattern of the printed circuit board P. It is electrically connected to the terminal 31).

The printed circuit board P in the vibrating case 11 is filled with an elastic body 8 on the side of the opening 11a of the vibrating case 11, and the elastic body 8 is just the opening 1 of the vibrating case 11.
The vibration energy of the printed circuit board P, which is filled up to 1a and which also serves as the resonator 2 and the terminal block 3 due to the vibration of the vibrating body 1 at the time of wave transmission, is consumed by the resistance of the elastic body 8 having the vibration suppressing function. It plays a role in preventing excitation. The ends of the plus and minus terminals 31 and 32 protruding from the printed circuit board P having the function of the terminal base 3 project from the opening 11 a of the vibration case 11.

By the way, as shown in FIG. 2, the drip-proof ultrasonic microphone A having the above-mentioned structure holds the outer periphery thereof with a vibration isolator B to prevent the influence of external vibration noise, and also to provide the vibration isolator B. An acoustic horn C for obtaining an arbitrary directivity can be attached to the outer circumference of the device to prevent a malfunction due to side lobes or the like. That is, FIG. 3A shows the directivity of the drip-proof ultrasonic microphone A alone.
FIG. 3B shows the directivity when the acoustic horn C is attached. As shown in FIG. 3A, the single unit of the drip-proof ultrasonic microphone A is installed at the corner of the car and the distance between the car and the obstacle is shown. When the vehicle is used for detecting while being in the driver's seat, the directivity angle does not reach the entire corner of the vehicle and side lobes are generated, and the detection area becomes unstable. Therefore, the acoustic horn C is mounted. I try to solve this problem.

In the above description, an example in which the acoustic horn C is attached to control the directivity has been described.
(A) shows an embodiment in which a wide directivity drip-proof ultrasonic device capable of detecting the entire corner of a car without using the acoustic horn C is shown. In this embodiment, the outer circumference of the truncated cone-shaped drip-proof ultrasonic microphone A is held by the cushioning material E, and the outer circumference of the cushioning material E is held by the housing D.
Further, the top surface of the truncated cone-shaped drip-proof ultrasonic microphone A and the end surface of the cushioning material E are flush with each other.
The cushioning material E used in this embodiment is made of a material having an extremely low natural frequency as compared with the housing D, for example, rubber or the like, encloses the drip-proof ultrasonic microphone A, and is fitted into the housing, or Alternatively, room temperature curable rubber or the like serving as the cushioning material E may be filled. The end surface of the cushioning material E is flush with the top surface of the drip-proof ultrasonic microphone A,
Wide directivity control as shown in FIG. 4B and vibration noise from the outside of the drip-proof ultrasonic microphone A are prevented.

FIGS. 5A and 5B show still another embodiment. In this embodiment, a plurality of drip-proof ultrasonic microphones A are arranged and the plurality of drip-proof ultrasonic waves are arranged. The outer circumference of the microphone A is held by the cushioning material E, and the outer circumference of the cushioning material E is held by the housing D. The top surface of the plurality of drip-proof ultrasonic microphones A and the end surface of the cushioning material E are separated from each other. It is the same. In FIG. 5C, FIG.
The directivity in the example shown in (b) is shown.

Here, the housing D holding the cushioning material E
The outer shape of is not limited to a circular shape, and may be a rectangular shape or another shape. In the embodiment shown in FIGS. 4 and 5 as described above, wide directivity without side lobes is possible without using the long acoustic horn C as shown in FIG. 3, and the ultrasonic device is miniaturized. Also, directivity can be controlled by forming an array. Further, the arrangement shown in FIG. 5 has a wide directivity due to the arrangement of a plurality of drip-proof ultrasonic microphones A, and also enables high output by synthesizing sound pressure.

[0017]

As described above, according to the present invention, a vibrating case having a bottomed cylindrical shape and having a tapered portion on the bottom side,
A vibrating body having a piezoelectric element fixed to the inner surface of the bottom of the vibrating case, a printed circuit board serving as both a resonator and a terminal base fixed in the middle of the vibrating case, and an end portion protruding from the printed circuit board. Since each of the plus and minus terminals protruding from the opening of the vibration case and the elastic body filled in the opening of the vibration case of the printed circuit board in the vibration case constitute the drip-proof ultrasonic microphone, Since the printed circuit board shares the resonator and the terminal base, the cost is reduced and the assembly is simplified, and the elastic body filled in the opening of the vibration case of the printed circuit board also serves as the terminal block. The excitation of the substrate can be suppressed, the reverberation time can be shortened, and the short-distance detection performance can be improved.

[Brief description of drawings]

1 is a cross-sectional view of the present invention.

FIG. 2 (a) is a cross-sectional view showing an example supported by the above acoustic horn, and FIG. 2 (b) is a front view.

FIG. 3A is an explanatory diagram showing the directivity of a single drip-proof ultrasonic microphone, and FIG. 3B is an explanatory diagram showing the directivity when an acoustic horn is attached.

FIG. 4A is a cross-sectional view of an embodiment of a structure that controls wide directivity without using an acoustic horn and prevents intrusion of vibration noise from the outside of the drip-proof ultrasonic microphone;
(B) is explanatory drawing which shows the directivity same as the above.

FIG. 5A is a front view of another embodiment of the structure for controlling wide directivity and preventing intrusion of vibration noise from the outside of the drip-proof ultrasonic microphone without using an acoustic horn, 3B is a cross-sectional view of the same as above, and FIG. 3C is an explanatory view showing directivity of the same.

FIG. 6 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 P printed circuit board 1 vibrating body 2 resonator 3 terminal base 8 elastic body 11 vibrating case 11a opening 12 piezoelectric element 31 terminal 32 terminal

Claims (1)

[Claims] 1. A vibrating case having a bottomed cylindrical shape and having a tapered portion on the bottom side, a vibrating body having a piezoelectric element fixed to the inner surface of the bottom of the vibrating case, and a resonance fixed in the middle of the vibrating case. A printed circuit board that also serves as a body and a terminal base, plus and minus terminals protruding from the printed circuit board and having ends protruding from the opening of the vibration case, and the opening of the vibration case of the printed circuit board in the vibration case. A drip-proof ultrasonic microphone, characterized in that it is configured by an elastic body filled on the side of the part.